Libby/Hurley Theory
So this just randomly popped into my head, and I can't really remember any details about some things so any help would be great.
I think we can say that what landed Hurley in the nuthouse was his little dock accident, in which a few people were killed (right?).
While talking to Desmond, Libby said that her husband died. I'm not sure how long ago she said that was, but the timing seems right so that it's possible that her husband was killed in Hurley's little accident (plus, he was a boat owner). [If Libby came right out and said how he died, please tell me because I don't trust myself to remember anything.]
So... maybe the same accident that sent Hurley to the nuthouse sent Libby there too, after the death of her husband. And maybe that obsessive staring of hers in Hurley's flashback was because she recognized him, but by the time she saw him on the island she had dealt with everything and forgiven him. I'm not sure how likely it is that she would begin to fall for the guy who was responsible for her husband's death, but hey, it's LOST.
Does that sound somewhat reasonable?